Select the cell or range of cells containing the numbers
Right-click and choose Format Cells
Go to the Number tab
Select Number, Currency, Accounting, Date, Time, Percentage, or Text as needed
Adjust decimal places if required
Click OK
Use the Home tab and choose the desired number format from the Number group
Use keyboard shortcuts such as Ctrl+1 to open Format Cells
If converting text numbers to real numbers, use Data > Text to Columns and finish the wizard
If needed, use the VALUE function to convert text to numbers
Copy the result and paste values if you want to replace formulas with fixed numbers